New Delhi: A latest census of plants has estimated that there are 391,000 plant species of which 369,000 are flowering plants and that one in five plant species is threatened with extinction. The report titled State of the World’s Plants 2016 is authored by the Britain-based Royal Botanic Gardens, Kew.

The report revealed that 2,034 plant species were discovered and described in the International Plant Names Index in 2015. The top three source countries for the identification of new species of vascular plants are Australia, Brazil and China.

The report was prepared by a team of researchers which reviewed published literature, analysed global databases and new datasets. “This is the first ever global assessment on the state of the world’s plants. I find this remarkable given the importance of plants to all of our lives–from food, medicines, clothing, building materials and biofuels, to climate regulation,” said Kathy Willis, director of science at the Royal Botanic Gardens, Kew. “This report therefore provides the first step in filling this critical knowledge gap,” Willis added.

Out of all the new species described in 2015, the largest and heaviest was Gilbertiodendron maximum weighing an estimated 105 tonnes with a height of up to 45 meters which was found in the Cameroon-Congolian African rain forest. The species is critically endangered. Other new species included more than 90 species of Begonia, 13 new species from the onion family, and discovery of a close relative of sweet potato.

In the past decade, every year, more than 2,000 new plant species are discovered and described.

Twenty-one percent of global plant species are currently threatened with extinction, according to IUCN Red list criteria. Several of the new species published in 2015 are already presumed extinct as a result of forest habitats destroyed by fires, agricultural activity, and other human activities such as diamond mining. The report identified 1,771 important plant areas out of which very few are under conservation protection. The report warned that these areas are degrading or disappearing entirely under the assault of increasing threats including land-use change, climate change, pests and diseases.

But the report highlighted that invasive species are one of the most important drivers of biodiversity loss. “Around 5,000 species are now documented as invasive in global surveys. These plants are causing large declines in native plants, damaging natural ecosystems, transforming land-cover and often causing huge economic losses,” said the report. The primary introducer of invasive plant species is international trade.

When it comes to useful plants, at least 31,000 plant species have published use such as medicines, food and material. The report stressed on the need for more research effort to pool genetic variation in gene banks. More than 3,500 crop wild relatives are prioritised for collecting and preservation in gene banks, according to the report, which are spread out in wide-ranging locations and are important for the future of food security.